arduino/Arduino — pull request #1798 by matthijskooijman (2014-01-09 18:44:30+00:00)
Title: Make some operators in IPAddress const

These functions do not modify the IPAddress object, but were not marked
as const. This meant that you could not do:

void set_ip(const IPAddress& ip) {
this->ip = ip;
}

Since calling operator uint32_t() on ip would discard the constness of
the reference.